Memory: functions and types (sensory, short and long term)

We review the characteristics of the short and long term memory, and also explicit memory, among others
Types of memory and characteristics | iStock

Memory is one of the most unknown and exciting faculties of the human brain. By learning more about its main characteristics and functions we can get to know ourselves better and establish guidelines to improve our intellectual performance.

In this article, we will explain what memory is, what its functions are, and what types there are -including short and long term memory, among others. We will also review the main disorders and alterations that can affect memory.

What is memory?

Memory is one of the basic functions that the human brain uses in an evolutionary way to survive. This special faculty allows human beings to store relevant information of any kind as well as to retrieve it at any time, among other essential processes.

Memory has been, since the appearance of the human being, an essential faculty for the survival of the species, as it is for almost all animal species in the world.

It eases learning, the transmission of knowledge between generations, general knowledge about the environment, and also about the dangers and threats it entails.

Memory is one of the most versatile cognitive faculties and one that has the greatest plasticity of all human capacities. Over time, people have managed to find mechanisms and strategies to improve memory, as well as to get the best out of it.

Functions of this essential human faculty

Human memory performs three essential types of processes: encoding, storage and retrieval of mnemic information.

In each of these processes (or phases) different faculties related to memory intervene and, at the same time, each of the three can be interfered with by certain elements.

Below, we review the characteristics of each of the phases involved in the functioning of memory.

1. Encoding

The encoding memory phase consists of receiving information from the medium in which we are and transforming that information into a code with which the memory can operate.

Generally, the code is either verbal (words, concepts, numbers, letters...) or visual, in this case consisting of images, landscapes, or shapes.

The encoding phase, since it depends on the person's senses and the correct functioning capacity of the brain, is generally fallible, that is, it is not always done well and sometimes errors are produced.

2. Storage

Memory storage is the process by which encoded information in a language understandable to the brain is saved in order not to be lost and used in the future.

This information can be stored for hours, days or even a lifetime, which configures the different types of memories existing in human memory.

Again, different elements can interfere with the correct functioning of the memory. The main circumstances that can affect this process are the state of the person's memory, the presence of contusions, trauma or pathologies of any kind, and neuronal and physical aging.

3. Retrieval

Retrieval means, of course, evoking, remembering, and reprocessing previously stored information.

The main problems when remembering may be due, again, to the natural aging of the person or to some pathology affecting memory, such as amnesia.

Types of memory depending on their characteristics

According to the classic categorization of memory, we find 3 different types according to their nature and distinctive characteristics.

1. Sensory memory

Sensory memory is the type of memory that humans obtain from physical senses. It is the most primary process of memory and is prior to any other higher type of memory process.

Sensory memory is the first step in the process of memorizing events and focuses mainly on the stimuli obtained by sight, hearing, taste, smell and proprioception.

Memory is a complex process involving many different elements in our brain that are responsible for processing a large amount of information from the outside world. Sensory memory is the part of the memory that receives stimuli from our physical body, that is, the immediate sensations we experience.

2. Short term memory

Short term memory or working memory is the one that processes the memories needed to carry out tasks just at the moment the person is and related to the immediate environment.

This type of memory is triggered when a person needs to memorize items for a short time in a variety of settings -during a board game, grocery shopping, teamwork, or writing a letter, for example.

Short term memory is more durable than sensory memory but less durable than long-term memory. It is estimated that this type of memory is limited to remembering between 2 and 7 elements for approximately 30 seconds.

3. Long term memory

This type of memory is called like that because it is the most durable, and the one in charge of remembering any element with hardly any limit of quantity or storage time.

Long term memory is the one in charge of remembering emotionally relevant knowledge or contents that have remained in the person's mind for some reason.

Some examples of memories stored in long-term memory are one's own name and those of our loved ones, as well as physical appearance, general culture data related to history or geography, and knowledge learned through memorization, such as what we studied during childhood.

Within long term memory, we find declarative or explicit and non-declarative memory. Declarative memory refers to knowledge about the world and can be codified in words or numbers, from important dates in our lives to historical, geographical, or linguistic data.

On the contrary, non-declarative or procedural memory is not made explicit with verbal codes but is what we need to do things, to develop activities or to use practical knowledge.

References:

  • Bauer, P.J.; Wiebe, S.A.; Carver, L.J.; Waters, J.M.; Nelson, C.A. (2003). Developments in long-term explicit memory late in the first year of life: behavioral and electrophysiological indices. Psychol Sci, 14 (6): 629–35.

  • Davelaar, E. J.; Goshen-Gottstein, Y.; Haarmann, H. J.; Usher, M.; Usher, M (2005). The demise of short-term memory revisited: empirical and computational investigation of recency effects. Psychological Review, 112 (1): 3–42.

  • Nikolić, D.; Singer, W. (2007). Creation of visual long-term memory. Perception & Psychophysics, 69 (6): 904–912.

  • Oberauer, K.; Kliegl, R. (2006). A formal model of capacity limits in working memory. Journal of Memory and Language, 55 (4): 601–626.

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